Method and System for Logic Equivalence Checking

1. A computer implemented method of circuit equivalence checking, comprising: solving at least a first equivalence checking problem, wherein the act of solving at least the first equivalence checking problem is performed by a processor; storing at least a first solution to at least the first equivalence checking problem; reusing at least part of the first solution to the first equivalence checking problem for a second equivalence checking problem, wherein the first equivalence checking problem includes comparing logic cones and the first solution includes one or more problem signatures, the first solution includes one or more stored problems, and the one or more stored problems permit matching between stored and searching logic cone pairs; and storing the one or more problem signatures in a memory.

2. The computer implemented method of claim 1 , wherein the one or more problem signatures includes previously compared logic cones.

3. The computer implemented method of claim 1 , wherein the one or more problem signatures includes hash values of previously compared logic cones.

4. The computer implemented method of claim 1 , wherein the one or more problem signatures includes counts of primary inputs and primary outputs.

5. The computer implemented method of claim 1 , wherein the one or more problem signatures includes counts of logic gates.

6. The computer implemented method of claim 5 , wherein the one or more problem signatures includes counts of logic gates of different logic gate type.

7. The computer implemented method of claim 1 , wherein the one or more problem signatures includes quasi canonical numbers associated with graph colorings of compared logic cones.

8. The computer implemented method of claim 1 , wherein the one or more problem signatures includes RTL expressions.

9. The computer implemented method of claim 1 , wherein the one or more problem signatures includes RTL key point type counts.

10. The computer implemented method of claim 1 , wherein the one or more problem signatures includes RTL key point types.

11. The computer implemented method of claim 1 , wherein the first solution includes one or more algorithm traces.

12. The computer implemented method of claim 11 , wherein the one or more algorithm traces includes a list of algorithms used for comparing logic cones.

13. The computer implemented method of claim 11 , wherein the one or more algorithm traces includes an order of algorithms used for comparing logic cones.

14. The computer implemented method of claim 11 , wherein the one or more algorithm traces includes one or more intermediate values of algorithms used for comparing logic cones.

15. The computer implemented method of claim 11 , wherein the one or more algorithm traces includes one or more final results of algorithms used for comparing logic cones.

16. The computer implemented method of claim 1 , wherein the first solution includes one or more stored problems, wherein the one or more stored problems permit exact matching between stored and searched logic cone pairs.

17. An apparatus for circuit equivalence checking, comprising: a processor configured for solving at least a first equivalence checking problem; means for storing at least a first solution to at least the first equivalence checking problem; means for reusing at least part of the first solution to the first equivalence checking problem for a second equivalence checking problem, wherein the first equivalence checking problem includes comparing logic cones and wherein the first solution includes one or more problem signatures, the first solution includes one or more stored problems, and the one or more stored problems permit matching between stored and searched logic cone pairs; and a memory for storing the one or more problem signatures.

18. The apparatus of claim 17 , wherein the one or more problem signatures includes previously compared logic cones.

19. The apparatus of claim 17 , wherein the one or more problem signatures includes hash values of previously compared logic cones.

20. The apparatus of claim 17 , wherein the one or more problem signatures includes quasi canonical numbers associated with graph colorings of compared logic cones.

21. A computer readable medium comprising a computer program stored in a storage medium or a memory medium which, when executed by a processing system, causes the processing system to perform the process of circuit equivalence checking, the process comprising: solving at least a first equivalence checking problem, wherein the act of solving at least the first equivalence checking problem is performed by a processor; storing at least a first solution to at least the first equivalence checking problem; reusing at least part of the first solution to the first equivalence checking problem for a second equivalence checking problem, wherein the first equivalence checking problem includes comparing logic cones and the first solution includes one or more problem signatures, the first solution includes one or more stored problems, and the one or more stored problems permit matching between stored and searched logic cone pairs; and storing the one or more problem signatures in a memory.

22. The medium of claim 21 , wherein the one or more problem signatures includes previously compared logic cones.

23. The medium of claim 21 , wherein the one or more problem signatures includes hash values of previously compared logic cones.

24. The medium of claim 21 , wherein the one or more problem signatures includes quasi canonical numbers associated with graph colorings of compared logic cones.

25. The medium of claim 21 , wherein the first solution includes one or more stored problems.